Adjustment Method - JVC MX-GT98V Service Manual

Adjustment method

Measurement instruments required
for adjustment
1. Low frequency oscillator,
This oscillator should have a capacity to output 0dBs
to 600ohm at an oscillation frequency of 50Hz-20kHz.
2. Attenuator impedance : 600ohm
3. Electronic voltmeter
4. Frequency counter
5. Wow flutter meter
6. Test tape
VT703L : Head azimuth
VT712 : For Tape speed and wow flutter ( 3kHz)
VT724 : For Reference level (1kHz)
VT703L : For Head angle(10kHz)
7. Blank tape
TAPE : AC-225,
8. Torque gauge : For play and back tension
Forward ; TW2111A, Reverse ; TW2121A
Fast Forward and Rewind ; TW2231A
9. Test disc
: CTS-1000(12cm),GRG-1211(8cm)
10. Jitter meter
Measurement conditions
Power supply voltage
AC110/127/230-240V(50/60Hz): US,UN model
Measurement
output terminal : Speaker out
: TP101(Mesuring for TUNER/DECK/CD)
: Dummy load 6ohm
MX-GT98V/MX-GT95V/MX-GT88V
MX-GT85V/MX-G78V/MX-G75V
Radio input signal
AM modulation frequency : 400Hz
Modulation factor : 30%
FM modulation frequency : 400Hz
Frequency displacement : 22.5kHz
Frequency Range
AM 531kHz~1710kHz : US,UN model
FM 87.5MHz~108MHz
Standard measurement positions of volume
and switch
Power : Standby (Light STANDBY Indicator)
Sub woofer VOL. : Minimum
Sound mode : OFF
Main VOL. : 0 Minimum
Traverse mecha set position : Disc 1
Mic MIX VOL : MAX (Only US,UN ver.)
ECHO : OFF
Precautions for measurement
1. Apply 30pF and 33kohm to the IF sweeper output
side and 0.082 F and 100kohm in series to
the sweeper input side.
2. The IF sweeper output level should be made as
low as possible within the adjustable range.
3. Since the IF sweeper is a fixed device, there is
no need to adjust this sweeper.
4. Since a ceramic oscillator is used, there is no need
to perform any MPX adjustment.
5. Since a fixed coil is used, there is no need to adjust
the FM tracking.
6. The input and output earth systems are separated.
In case of simultaneously measuring the voltage
in both of the input and output systems with an
electronic voltmeter for two channels, therefore,
the earth should be connected particularly.
7. In the case of BTL connection amplifier, the minus
terminal of speaker is not for earthing. Therefore,
be sure not to connect any other earth terminal
to this terminal. This system is of an OTL system.
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